Controllable-pitch propeller



Sept.

22, 1942. E. MARTIN ETAL' 2,296,288 CONTRLLABLE-ITGH PRPELLER Filedsept. 7, 1958 '2 Sheets-Sheet l mln ' INVENTOR.,

' r ERLE MAm-m W A FL 2 Y Jol-1N E. ANDERSON MAA/f? M ATTORNEY Sept.22', 1942. E. MARTIN Erm. 2,296,288

' CONTROLLABLE-P-ITCH PROPELLER 2 A Filgd sept. 7,'1958 2 sheets-sheet 2INVENTOR ERL'E MARTIN 'N BY JOHN E; ANDERSON k! am M ATTORNEYillustration onl "'Petente'i'sept. 22,1542 I, v!

UNITED STATES, Plrrflzla'i OFFICE Comm-FITCH PROPILLER Ellmln,Werlnfotd, md John E. Andel'- ,m Portland,

Conn.,

n, East Hartford, Conn., a cor- Corporatio poration of Delawareapplicaties-september v, 193s, serial No. 228,772

' A1acalms. (ci. 12o-163i This invention relates to improvements incontrollable-pitch propellers and has' for an object the provision of,an improved propeller of the character specified, so constructed andarranged thatthe propeller has a range of speed regulating pitchchanglngmovements and a range of pitch changing movements beyond saidspeed regulating range in which the propeller is brought into and outofa feathered condition.

A further object resides in the provision of a controllable-pitchpropeller ofthe character described having hydraulically actuated meansfor turning the propeller blades to change the pitch thereof, in whichthe pitch changing mechanism,- iiuid pressure accumulators andl a fluidpres-V sure pump are all in or closely associated with` the hub portionof the propeller to reduce the probability of leakage of fluid underpressure and render the oil passages of a minimum length to therebyreduce the friction of the fluid in flowing through such passages.

A still further object resides in the provision of a-controllable-pitchfeathering-type propeller,

lof the character indicated, so arranged that hydraulic fluid underpressure may be supplied to the pitch changing mechanism with sufficientthe propeller pitch from the operating range to a feathered condition.

Other objects and advantages will be more particularly pointed outhereinafter or will become apparent as the description proceeds.

In the accompanying drawings, in which like reference numerals are usedto designate similar parts throughout, there is illustratd, by way ofexample, a suitablemechanical embodiment of a propeller constructedaccording to the invention. The drawings, owever, are for the purpose ofand are not to be taken as in any way limiting or restricting the scopeof the invention as set forth in the accompanying claims.

In the drawings,

Fig. 1 is a vertical sectional view of the hub Vportion of a'propellerconstructed according to the invention and a schematic arrangement of agovernor and feathering control pump for controlling the pitch of thepropeller.

Fig. 2' isl a sectional view of a pitch changing motor vane, taken onthe line 2-2 of Fig. 1.

Fig. 3 is a'schemati'c sectional view of the hub portion of thepropeller shown in Fig. 1 showing rs to Unlied Airfragmentary portion ofthe propeller construction illustrated in Fig. 1 showing the propellerpitch controlling valve in an operative position different from thepositions shown in Figs. 1

and 4 and f Fig. 6 is a sectional view of the propeller blade turningmechanism taken on the line 6-6 of Fig. 3 looking in the direction ofthe arrows.

Referring to the `drawings in detail, the nu` meral Il generallyindicates a propeller driving theY hollow interior is divided by asecond tapered plug I8 located in the interior of the drive shaft4adjacent to the plane of the bearing ill. This -plug is provided withholes or apertures 26 con.- necting the two portions of the interior ofthe drive shaft and receives the rear end of a tube 22 which issubstantially coaxial with the drive Vshaftand projects forwardly to alocation adjacent'to the forward end of the plug i6. Immediately withinthe bearing receiving portion of the nose piece of the engine the driveshaft i2 is surrounded by a bushing 24 having an internal annular groove26 connectedby means oi a transverse, apertured tube 28, with a chamber30 in the plug I8 into which the rear end of the tube 22 extends so thatthe tube 22 is hydraulically connected with the channel 26. An oilcollector ring ortransfer bearing 32 is rigidly attached to the enginenose piece and provided with a cylindrical-portion closely surroundingthe exterior of the bushing 24. The bushing is provided with an exteriorannular groove 34 connected to the interior channel 26 by apertures, asindicated at 36, and two pairs of sealing`rings, as indicated at 38and,40, are disposed one pair on each sideof the external groove 34between l .the bushing 24 and the bushing surrounding porthe arrangementof the various uid passages and connections.

Fig. 4 is a sectional view of a fragmentary portion of the propellerillustrated in Fig. 1 show-' ing the propeller pitch controlling valveinv an operativefposition different from the positio illustrated in Fig.1.

' Fig. 5 is a sectional view similar to Fig.- 4 of a ltion of the oilcollector Iring 32, to provide a suitable means for transferring fluidunder pressure from the interior of the hollow drive shaft to arelatively fixed member outsideof the drive be operated by a manuallycontrolled motor or by hand as may be convenient or desired.

A spider member, generally indicated at 50, `has .agenerally'cylindrical portion 52 mounted upon the splined end of thedrive shaft i2 and retained thereon by suitable means such as the cones54 and 56 and Vnuts 58 and 60; and a plurality of integral hollow bladecarrying arms, as indicated at 62, projecting radially from thecylindrical i shaft receiving portion. A propeller blade, as indicatedat 64, having a hollow flanged root or base end is rotatably mountedupon eachspider arm 62 and retained thereon by barrel member;

arms and'each bushing is provided at its inner end with an outwardlyextending radial flange portion l2 underlying the base end of the bladeand an integral annular ilange portion 14 which extends inwardly fromthe periphery of the ange 'l2 to an annular fluid seal I6 mounted in acircular groove in the shaft receiving portion of the spider immediatelysurrounding the root end of each respective blade carrying arm 62.'I'his arrangement provides an annular space '|8, of substantiallyrectangular cross section, immedi ately surrounding the base end of eachblade carrying arm. Respective blade turning motors are provided bydisposing relatively movable vanes in 'the annular spaces 18. As isparticularly shown in Fig. 6, two diametrically opposed vanes, asindicated at 80 and 82, are secured to the nanged portion l2 of eachbushing 10 and two similar diametrically opposed vanes, as indicated at84 and 86 in Fig. 6, are secured to the portion of the spider 50 withinthe groove for the annular seal 16. With this arrangement the blade maybe made to rotate in either direction by applying hydraulic fluid underpressure between appropriate sides of adjacent sleeve carried and spidercarried vanes in a manner well known to the art. In order to minimizeleakage past the vane and increase the eiiiciency of the vane typemotors each vane comprises a slotted extension integral with the sleeveflange or spider, as indicated at 88 in Fig. 2, supporting a pluralityof wiper blades, as indicated at 90, said blades being provided withapertures somewhat out of registry with each other and being urgedtoward the four corners of the rectangular cross section of thecorresponding space 'I8 by a spring pressed tapered plug 92 extendingthrough said apertures.

'Ine pitch changing movements of all of the bladesv are synchronized andequalized by means of a rotatable bevel gear 94 rotatably mounted, bymeans of a suitable anti-friction bearing 96,

\ on the periphery of a circular supporting member 98 and provided withgear teeth which mesh with corresponding gear teeth provided on aportion of the periphery of the anged portion 'I2 of each o'f thebushings 62.

The application of hydraulic uid under pressure to the vane motorsconnected with the respective propeller blades is controlled by a slidevalve slidably mounted in a valve casing |02 secured in a coaxialaperture in the annular member 98 which member is carried by the nut 60at the outer end .of the propeller drive shaft I2. A pair of uidchannels, as indicated at |04 and |06 respectively, connect each of thevane motors with the slide valve casing |02 and a fluid pressure line|08 leads to the valve casing |02 from fluid pressure accumulatorsprovided in the hollow spider arms 62. yThe outer end of each hollowspider arm is stopped by a suitable plug,

each hollow arm there is provided a piston member I I 2 which worksagainst a compression spring II4 set for the pressure which it isdesired to maintain in the accumulators. A stem I| 6 projects throughthe piston member I|2 and spring ||4 into a chamber ||8 which interceptsa uid channel connecting the engine oil supply in the hollow drive shaftI2 with the pressure pump, generally indicated at |22. The arrangementof these parts is such that when the pressure in the accumulators hasreached the desired value the respective pistons I I2 are moved to forcethe ends of the stems ||6 into the receptacles ||8 and.

thereby cut of! the supply of oil at the desired pressure in thepressure accumulators at all times during operation of the engine. Inorder to facilitate operation of the above described as indicated atIIO, and in the inner portion of 75 valves the stems II6 may be extendedalong the axes of the arms 82 to a sliding connection with the en'dplugs IIO, as indicated at |24, to maintain the stems at'all times inperfect alignment` with the respective pistons II2 and receptaclesHydraulic tluid, such as engine lubricating oil, is continuouslysupplied to the interior of the hollow drive shaft I2 at all timesduring engine operation by a lubricating oil pump |26 which draws theoil from the engine oil sump |28 and forces it into the enginelubricating system. The pressure of the engine lubricating oil ismaintained at a preselected value by an oil pressure relief valve |30which by-passes excess oil supplied to the lubricating system by thepump |28, back to the sump |28.

The pump |22 is in the form of a wobble pump having a plurality of smallcylinders and pistons arranged in an annular member |32 disposed aroundthe rearward portion of the spider 50 and the adjacent portion of thedrive shaft I2 between the propeller hub and the front end of the enginenose piece. The annular member |32 is carried around with the spiderwhen the propeller rotates and the ends of the piston, as indicated at I34, bear against a'slightly skewed ball thrust bearing, one race ofwhich is secured in an annular member |36 which is rigidly secured tothe front end of the nose piece l0 and surrounds the rearward portion ofthe annular member |32. An oil seal |38 having a vent connection |40with the interior of the engine casing is provided between the members|36 and |32 to prevent leakage of oil past the pump to the exterior ofthe engine. The pump supply channels |20 lead to pump intake ports, onefor each pump cylinder, as indicated at |42, and the pump outlet ports,as indicated at |44, are connected with the several accumulators bysuitable iiuid channels, as particularly illustrated in Fig. 3 andindicated by the numeral |46. The several accumulators are preferablyconnected together by suitable channels so that the pressure in all ofthe accumulators will be equalized at all times. A bleed line |40 leadsfrom the iiuid pressure lines |08 to a chamber connected with the frontend of the tube 22. As has been explained above drainage from the tube22 is controlled by the governor 46.

When the oil supply to the pump is cut of! lby the pressure actuatedvalves ||6, as explained above, the pump pistons are held inwardly inthe .respective pistons by the suction thus produced,

and the pump is rendered inoperative whenever the pressure of the fluidin the accumulators is at the selectedvalue.

In the automatic constant-speed controlling action ofthe governor theremay be said to be viz: 4a "condition blades toward a higher pitchcondition.

which the engine speed is above the speed for which the governor is setin which case the governor-ily balls |62 move'outwardly to raise thevalve member |54 and open the drain from the Y `are moved inwardly tolower the valve stem |54 and cut off the drain from the tube 22. 'Ihepressure in the chamber |56 is controlled by the condition of the drainfrom the tube 22 and this pressure acts on the rearward end of the slidevalve |66 against the compression spring |56 to control the position ofthe slide valve. When the tube 22 is connected with drain, incident toan overspeed condition of the engine, the spring |56 will move the slidevalve to its limiting righthand position, which position is particularlyillustrated in Fig. 4. In this position of the slide valve the pressureconduit ||I6isv connected through the valve with the channels |66leading to the vane motors, the channels |66 being connected with themotors in a manner to rotate the propeller At the same time the channels|64 are connected by the slide valve 'I 66 with the double ported ,drainchannel |66 which vents to the interior of the hollow 'escasas tube 22;a second in which the engine is operatdrive shaft I2 against the enginelubricating oil 35 pressure, the pressure in the accumulators being Whenthe drain from the tube 22 is cut of! b lthe governor 46 incident to anunderspeed con- Aber |56 where it reactsagainst the rearward end of theslide valve: |66. The slide valve |66 is hollow and contains a checkball1|60 forced against its seat at the rear or right-hand end of theslide valve by a spring |62 which is more easily compressible than thespring |56. It is assumed that before the-pump 46 is operated to featherthe propeller the engine will have ceased operation or will have beenreduced to an idling condition so that there is no continuous supply ofiluid under high-pressure to the accumulators in the hollow spider arms.Under these conditions the pressure ysupplied bythe pump 48 moves thecheck ball |60 olf of its seat in the end of the slide valve |06,compressingv the spring |62, but the valve IMI itself does not moveappreciably against the force of the spring |56. The high-pressure uidthen flows from the tube 22 through the hollow 4interior of the slidevalve |66 to the channels |66 to turn the propeller blades to theirlimiting high-pitch position.

If, after the blades have been moved to their limiting high-pitchcondition or havebeen feathered, the pump 48 is again operated to applyhydraulic fluid at a still higher pressure to the valve |66, the slidevalve will be moved against the force of' the spring |56 until the portsleading through the wall ofthe valve from the hollow interior -thereofregister with the channels |64, as is shown in Fig. \5. The highpressureoil then flows through the channels |64 to the` vane motors to returnthe blades toward a low-pitch condition and Vthe oil in the portions ofthe motors supplied by the channels |66 drains back through this channeland the drain channels |56 tothe interior of the hollow drive shaft i2.

From the above description it will be seen that there has been providedan improved controllable-pitch propeller in which the high-pressure pumpand all of the high pressure fluid channels dition of the engine thefluid pressure in the valve |66 with the channels |64 and the channels|66 are connected with the drain channel |56 thereby causing a rotationof the propeller blades toward a lower pitch condition to decrease theload on the propeller driving engine and increase its speed.

When the governor is in the second or balanced condition mentioned abovethe slide valve |66 may assume anl intermediate position, such as is andconnections for automatic constant-speed control are located entirelywithin the-propeller hub to reduce the friction losses and timeintervals for the flow of hydraulic fluid from the pump to the pitchchanging motors, and avoid the danger of leakage from the high-pressurelines, and in which the only high-pressure pump connected with thepropeller through a connection having relatively rotatable parts is thefeathering and unfeathering pump which is used only on rare occasionsand when the engine is not rotating at high-speeds; and also an improvedpropeller construction having a range of blade positions for constantspeed regulation and a blade feathering position outside of theconstant-speed range to which position -the blades particularlyillustrated in Fig. 1 in which the 42 past thecheck valve 44. When thepump 46 Vis operated the check valve 44 will be moved to rva position inwhich it connects the pump outlet conduit |66 directly with the channel42 and blocks the voutlet from the governor 46. The high-pressure fluidfrom the pump 46 enters the tube 22 through the collector ring 36 andbushing 26, transverse tube 26, and iiows to the chammay be rapidlymoved from the normal operating or constant-speed range.

While a particular mechanical embodiment has been hereinabove describedand illustrated' in the accompanying drawings 'for the purpose ofdisclosing the invention, it is to be understood that the invention isin no way limited to the particular construction and arrangementA soillustrated and described, but that such changes in the size, shape andarrangement of parts may be resorted to as come within the scope of thesub-joined claims.

Having now described the invention so that l by said hub structure forpitch changing rotational movements, a reversible vane type hydraulicmotor operatively associated with the hub supported end of each bladefor rotating the same,

a source of hydraulic pressure within said hub structure adjacenttosaidmotors, a drain leading from said hub structure, fluid passages whollywithin said hub structure between said pressure source and said motorsand between said motors v sages to control the application of pressureiluid to said reversible motors, speed responsive means operativelyassociated with said valve to regulate the pitch of said propeller in anintermediate 'range f pitch adjustment, and manually operable means forcontrolling said valve and supplying hydraulic iluid under pressure tosaid motors to move said propeller into and out of its extremehigh-pitch condition.

5.,In a controllable-pitch propeller having a hub structure and aplurality of blades support-v ed by said h ub structure for pitchchanging rotational movements, a reversible vane type hydraulic motoroperatively associated with the hub supported end of each blade forrotating the respective blades, a source of hydraulic pressure withinsaid hub structure, a uid drain hub structure and a plurality of bladessupported by said hub structure for pitch changing rotational movements,a reversible vane type hydraulic motor operatively associated with thehub supported end of each blade for rotating the same, a source ofhydraulic pressure within said hub structure, a drain leading from saidhub structure, fluid-passages wholly within said hub structure betweensaid pressure source and said motors and between said motors and saiddrain, a pressure operated valve also disposed within said hub structureintercepting said fluid passages to control the application of pressureiiuid to said reversible motors, speed responsive means for controllingsaid valve to regulate thepitch of said propeller, a hydraulicconnection between said pressure source and said valve, and a hydraulicconnection between said speed responsive means and said valve.

3. In a controllable-pitch propeller having a hub structure and aplurality of blades supported by said hub str ture for pitch changingrotational movements', a reversible vane type hydraulic motoroperatively associated with the hub supported end of each blader forrotating the same, a source of hydraulic pressure within said hubstructure, a drain leading from said hub structure, uid passages Whollywithin said hub structure between said pressure source and said motorsand between said motors and said drain, a pressure operated Valve alsodisposed within said hub'structure intercepting said uid passages tocontrol the application of pressure uid to said reversible motors, speedresponsive means for controlling said valve to regulate the pitch ofsaid propeller in an intermediate range of pitch adjustment, manualmeans for controlling said' valve to move said propeller into and out ofits extreme high-pitch condition, and a system of hydraulic conduitsconnecting said speed responsive means, said manual means and said hubstructure intercepting said uid pasleading from said hub structure,fluid passages wholly within said hub structure between usaid pressuresource and said motors and between said.motors and said drain, a uidpressure operated-valve also disposed within said hub structureintercepting said iluidJpassages to control the application of pressureiiuid to said reversible motors, a pressure chamber operativelyassociated with said valve, and speed responsive means for controllingsaid valve by regulating the iluid pressure in said pressure chamber,and a hydraulic connection between said pressure chamber and said speedresponsive means.

6. In a controllable-pitch propeller having a hub structure and aplurality of blades supported by said hub structure for pitch changingrotational movements, a reversible vane type hydraulic motor operativelyassociated Withthe hub supported end of each blade for rotating. saidblades to change the pitch of the propeller, a source of hydraulicpressure comprising pressure accumulators carried by said hub structureand an engine driven pump mounted on said hub structure and `connectedwith said accumulators, means for supplying hydraulic iiuid at arelatively low pressure to said pump from a iiuid source outsideA ofsaid hub, a drain connection leading from said hub structure, fluidpassages wholly within said hub structure between said pressureaccumulators and said motors and between said motors and said drain, avalve also disposed within said hub structure intercepting said iluidpassages to control the application of fluid under pressure to saidreversible motors, means outside of said hubffor controlling said valveto regulate' the pitch of said propeller, and means passing from theexterior of said hub to the interior thereof for operatively connectingsaid valve controlling means with said valve.

7*.In a controllable-pitch propeller having a hub structure and aplurality oi.' blades supported by said hub structure for pitch changingrotational movements, a reversible vane type hydraulic motor operativelyassociated with the hub supported end of each blade for rotating thesame, a source of hydraulic uid under pressure comprising pressureaccumulators disposed within said hub and an engine driven pump carriedby said hub and having inlet and outlet passages within said-hubstructure, passages for conducting hydraulic fluid to and from said hubstructure, the inlet passage being connected with the inlet o! saidpump, fluid passages wholly within said hub between said pressureaccumulators and said motors and between said motors and said drain, afluid pressure actuated valve intercepting said iluid passages tocontrol the application of fluid under pressure to said reversiblemotors, means for controlling said valve toregulate the pitch of saidpropeller, and a fluid channel between said valve controlling me andsaid valve.

mli combination with a controllable-pitch propeller and a propellerdriving engine, a hollow drive shaft supportingv and driving saidpropeller, means 'supplying engine lubricating oil at lubricating oilpressure to the interior of said hollow said motor with the interior ofsaid hollow drive shaft to return to said drive shaft oil withdrawntherefrom by said pump, a reversing valve in said propeller interceptingat least a portion of said fluid passages to control the application ofhighpressure hydraulic iiuid to said motor, means outside of saidpropeller for operating said valve,

and a connection between said controlling meansl and said valve.

9. In combination with a controllable-pitch propeller having a hub and aplurality of bladesl carried by said hub for pitch changing movements,and a propeller driving engine, a hollow` drive shaft supporting anddriving said propeller, means supplying engine lubricating oil atlubricating oil pressure to the interior of said hollow drive shaft, apump carried by said propeller hub arranged to withdraw oil from saiddrive shaft and increase the pressure thereof, an oil pressure.accumulator in said propeller hub connected with trolling said valve toregulate the pitch of said propeller.

10. In combination with a controllable-pitch propeller having a hub anda plurality of blades carried by said hub forpitch changing movements,and a propellerdriving engine, a hollow drive shaft supporting anddriving said propeller, means supplying engine lubricating oil atlubricating oil pressure to the interior of saidjdrive shaft, a pumpAcarried by said propeller arranged to withdraw oil from said driveshaft and increase the pressure thereof, a pitch changing hydraulicmotor operatively associated with the h ub carried end of each propellerblade, fluid pressure accumulators in said propeller hub connected with,theoutlet of said pump, fluid passages connecting said accumulatorswith said motors and said motors with the interior of said hollow driveshaft forv conductingV high-pressure oil to said motors and exhaust 4oilfrom said motors to the interior of said drive shaft, a valveintercepting said passages to controlthe application of hydraulic fluidto said motors, means for controlling said valve to regulate the pitchof said propeller, A l and means associated with said accumulators forcutting off the oil supply from said hollow drive shaft to said pump andrendering said pump inoperative when the pressure of oil in saidaccumulators lreaches a predetermined value.

1i. In combination wan' s controllable-pitch propeller having a hubspider adapted to be mounted on a drive shaft and provided with a.plurality ofhollow blade carrying arms, a blade rotatably mounted forpitch changing movement on each arm, and means for retaining said bladeson said arms, means closing the ends of said arms to form closedchambers in said hollow blade carrying arms, a pitch changing motoroperatively associated with each propeller blade, a fluid pressurepump.y a drain, means connecting the outlet of said pump with saidchambers to admit fluid from said pump into' said chambers, resilientmeans in each chamber for applying pressure to fluid contained therein,means connecting said motors with said chambers and with said drain, anda valve intercepting said motor connecting means for controlling theapplication of fluid under pressure from said chambers to said motorsandfrom said motors to said drain.

12. In a Vcontrollable-pitch propeller having a hub spider adapted to bemounted on a hollow drive shaft and provided with a plurality of hollowblade carrying arms, a blade rotatably mounted for pitch changingmovements on each arm, and means for retaining said blades on said arms,at least one motor for turning said blades, a drain for said motor, apump adapted to withdraw oil from said hollow drive shaft and increasethe pressure thereof, means closing the end of said hollow spider armsto form closed chambers, means connecting said chambers with said motorand said motor with said drain, valve means in said connecting means forcontrolling said motor, means connecting the outlet of said pump withsaid chambers.. a movable piston in the inner portion of each chamber, aspring opposing inward movement of each piston, and a valve stemactuated by each piston to control the supply of Aoil tosaid pump inaccordance with the oil pressure in said chambers.

13. In a controllable-pitch propeller having a hub spider adapted to bemounted on a hollow drive shaft and provided with 'a plurality .ofhollow blade carrying arms, a bladel rotatably mounted for pitchchanging'movement on each arm, and means for retaining said blades onsaid arms, a bushing in each blade and surrounding the respective spiderarm, each bushing having a hollow annular base to provide annular spacesaround the inner ends of the respective spider arms between th'erespective blade ends and said hub spider, a plurality of vanes in eachannular space alternately connected to the respective ,bushing and tosaid spider and located entirely outside of said blades, and means foradmitting hydraulic fluid under pressure to said annular spaces to'rotate said bushings and said blades in either direction with respect tosaid spider =arms to change the pitch'of said propeller,

14. In a controllable-pitch propeller `having a hub spider adapted to bemounted on a drive shaft and provided with' a plurality of radiallyextending blade carrying arms, a blade rotatably -mounted for pitchchanging movements on each arm, and means for retaining said blades onsaid arms, a bushing in each blade end surrounding the respective spiderarm, each bushing having a hollow annular base to-provide an annular:space of substantially rectangular cross-section around the inner endsof the respective spider arms, a plurality of vanes in each annularspace connected alternatively to the respective bushing and to saidspider, each vane comprising a 75 slotted support and a plurality ofplates loosely carried in each slot and resiliently urged toward thefour corners of the substantially rectangular section of sa'id annularspace, and means for admitting hydraulic uid under pressure to saidannular spaces to rotate said bushings and said blades in eitherdirection with respect to said spider arms to change the pitch of saidpropeller,

15. In va controllable-pitch propeller having a hub spider adapted to bemounted on a hollow drive shaft and provided with' a plurality ofradially extending blade carryingarms, ablade rotatably mounted forpitch changing movements on each arm, and means for retaining saidblades on said arms, a bushing in each blade end surrounding therespective spider arms and rigidly secured to the respective blades eachbushing having a hollow annular base to provide an annular space ofsubstantially rectangueach other when said plates are assembled in saidslots and disposed in said annular space, and a Aspring pressed taperedplug extending'through' said excentrically disposed apertures to urgesaid plate toward the four corners of the substantially rectangularcross-section of said annular spaces, and means for admitting hydraulicuid under pressure to said annular spaces to rotate said bushing andsaid blades in either direction with respect to the respective spiderarms to change the pitch of said propeller.

16. In combination with a controllable-pitch propeller having a hub anda plurality of blades carried by said hub for pitch' changing movements,and a propeller driving engine, a hollow drive shaft supporting anddriving said propeller, means maintaining a supply of engine lubricatingoil at engine lubricating oil pressure in said hollow drive shaft, apump carried by said hub and connected with the interior of said hollowdrive shaft operative to withdraw oil from said drive shaft and increasethe pressure of said oil, pitch changing motors and a control valvetherefor also carried by said hub and connected through said hub withthe outlet of said pump, a pressure chamber in said hub for operatingsaid valve, a restricted connection between said pressure chamber andsaid pump outlet, means outside of said hub for controllingv said valveby regulating the drainage of oil.from said pressure chamber,

and means including a slip ring around said drive shaft forhydraulicallyv connecting said valve controlling means with saidpressure chamber, whereby only drainage oilpasses through said slip ringconnection. v

17. In combination with' a controllable-pitch propeller having a hub anda plurality of blades carried by said hub for pitch changing movements,and a propeller driving engine, a hollow drive shaft supporting anddriving said propeller, means maintaining a supply of engine lubricatingoil at engine lubricating oil pressure in said hollow drive shaft, apump carried by said hub and connected with the interior of said driveshaft operative to withdraw oil from said engine oil supply and increasethe pressure thereof,

' means connecting said motor with said drain, f

pitch changing motors and a control valve therefor also ccarried by saidhub and connected through said hub with said pump, a pressure chamber insaid hub for operating said valve, a restricted connection between saidpressure chamber and said pump, means outside of said hub forcontrolling said valve by regulating the ments, and a propeller drivingengine, a hollow drive shaft supporting and driving said propeller,means maintaining a supply of engine lubricating oil atenginelubri'cating oil pressure in said hollow drive shaft, a pumpcarried by said hub and connected with the interior of said hollow driveI shaft to withdraw engine lubricating oil from said hollow drive shaftand increase the pressure thereof, pitch changing motors and a controlvalve therefor in said hub and connected through said hub with theoutlet of said pump, a pressure chamber in said hub for operating saidvalve, a restricted passage connecting said pressure chamber with saidpump outlet, speed responsive means outside of said hub for controllingsaid valve in an intermediate pitch range by regulating he drainage ofoil from said pressure chamber, a connec. tion between said speedresponsive means and said pressure chamber including a tube within saiddrive shaft connected at one end with said pressure chamber, a slip ringon the outside of said shaft connected with the opposite end of saidtube, and a conduit between the stationary portion of said slip ring andsaid speed responsive means, and a relatively stationary pressure pumpconnected with said pressure chamber through said slip ring to controlsaid valve and supply fluid under high pressure 'to said pitch changingmotors to turn said propeller blades to a feathered position beyond saidintermediate range of pitch adjustment.

19. In a controllable-pitch propeller having a hub spider adapted to bemounted on a hollow drive shaft and provided with a plurality of hollowblade carrying arms, a blade rotatably mounted for pitch changingmovement on each arm, and means for retaining said blades on said arms,at least one hydraulically actuated motor for turning said blades, adrain for said motor, a pump, means closing the ends of said hollowspider arms vto form closed chambers therein, resilient means in saidchambers compressible by uidunderpressure introduced into said chambers,means connecting said chambers with the outlet of said pump and withsaid motor and valve means intersecting said connecting means forcontrolling said motor, means supplying the inlet of said pump withhydraulic fluid, and valve means associated with at least one of saidchambers to interrupt said fluid supply whenever the pressure ofhydraulic uid in said chamber reaches a predetermined value. f

ERLE MARTIN.

JOHN. E. ANDERSON.

